The basic features of bipolar incompatibility in the hymenomycete, Polyporus palustris (Berk. and Curt.), have been investigated by a comparison of compatible and incompatible interactions leading to the formation of dikaryons and common‐factor heterokaryons, respectively. Nuclear migration is severely restricted and nuclear pairing and conjugate nuclear division fail to occur in the interaction of incompatible homokaryons. It is suggested that the single incompatibility factor of P. palustris combines the functions of the two incompatibility factors of tetrapolar species.
This paper describes the goals and preliminary work of Project Math-Muse, an interdisciplinary team of university and public school educators working with children's museums to design and evaluate interactive mathematics exhibits for young children. Authors discuss the rationale for the development of small, interactive mathematics exhibits for young children, based on the goal of matching (a) reform-based views of mathematics, which emphasize children's active, hands-on engagement in meaningful activities, with (b) the principles that guide children's museums. Observations of children and adults interacting with two exhibit prototypes developed at a local children's museum are presented along with discussions of some of the issues that have arisen in this work so far. The paper concludes with directions for continued work. 285 286 GUBERMAN ET AL. + PROJECT MATH-MUSE
Sexual morphogenesis in Schizophyllum commune, a higher basidiomycete, is controlled by two incompatibility factors, A and B. A key event, the migration of nuclei from each mate throughout the mycelium of the other, is controlled by the B factor and occurs in A = B ≠ matings. The distribution of nuclei in the resulting heterokaryon is irregular, and anucleate, uninucleate, binucleate and multinucleate cells are found. A similar distribution of nuclei is found in homokaryons carrying a mutation in the B factor. Because of their developmental history, strains that carry a mutated B factor offer a relatively simple system for the study of the events associated with nuclear migration. Growth of mutant-B germlings occurs in three stages: (I) most cells are binucleate; (II) most cells are uninucleate; (III) cells contain varied numbers of nuclei. The ratio of nuclei; cells remains constant during the transition from stage II to stage III. Changes in nuclear distribution result from movement of the nuclei from cell to cell, and the movement is associated with the disruption of the dolipore septum. The mutant-B system appears to offer an opportunity for the biochemical resolution of the events related to nuclear migration.
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